Calculate Distance Between Two Coordinates And Determine How Much Of Which Axis To Increment / Decrement

Basically I'm looking for a way to make one object follow another. For example, if I move object A to one area of the screen I want object B to to move to object A's location but I also want object B to move at a fixed speed (movement variable). How do I go about doing this?

Both the x and y coordinates of object B would need to know the coordinates of object A to calculate the distance between the two and to determine how much of which axis to increment/decrement (if that makes sense?) with the inclusion of the speed variable. In other words I'm just trying to create a homing object.